//构造函数
var arr=new Array();
console.log(arr,arr.length);
var arr1=new Array(5);
console.log(arr1,arr1.length);
// var arr2=new Array(1.1);
// console.log(arr2,arr.length);
var arr3=new Array('terry');
console.log(arr3,arr3[0],arr3.length);
var arr4=new Array('terry','hello',12,[1,2,3,4]);
console.log(arr4,arr4[3],arr4.length);
